The development trend for superhard material synthesis has clearly pointed toward larger press apparatuses (press enlargement) and the accuracy control of pressure and temperature. The digital control system, especially those based on Programmable Logic Controllers (PLC) and pressure sensor technology, was developed precisely to meet this need for precise control. It transforms the original unknown and passive control method into an active control method.
Here is a specific breakdown of how the digital control system satisfies the trend toward precision control in superhard material synthesis:

1. Achieving Precise Execution and Control of Process Parameters
In the synthesis process of artificial diamond or other superhard materials, the control of process parameters originates from setting heating parameters and controlling pressure parameters.
Execution and Storage of Process Curves: The digital system (composed of PLC, pressure sensors, and pressure gauges) can achieve the execution and storage of process parameter curves. The PLC controller enables the system to operate according to preset process curves (as shown in Figure 2), thereby achieving the desired synthesis effect.
Detailed Parameter Setting: Using the touch screen, operators can set a series of parameters in detail for precise control, such as: overpressure pressure, starting heating pressure, first stop pressure, pause time, second overpressure pressure, second stop pressure, second pause time, third overpressure pressure, final pressure, and soaking time.
Heating and Power Control: Various heating parameters can be controlled through programmed input via the PLC. By setting the required values, power or voltage can be precisely corresponded to different time periods, thus realizing the process curve shown in Figure 2.
Comprehensive Functionality: The PLC not only possesses functions like logical operation, real-time counting, and sequential control, but also features A/D, D/A conversion, data operation, and data processing. This provides the foundation for handling complex process data and achieving precise control.
2. Enhancing the Precise Synchronization of the Hydraulic System
In the application of the cubic press apparatus, the precision of synchronous pressure control across the six cylinders is crucial:
Scientific and Rapid Synchronization Adjustment: Previously, achieving six-cylinder pressure synchronization relied on repeatedly compressing solid blocks or ensuring consistent piston advance strokes. However, using the pressure gauge—a readily available "digital" system—to adjust the throttle valve is a scientific and rapid method for obtaining six-cylinder synchronous pressure.
Sustained Synchronous Pressure: By adjusting the system pressure corresponding to the throttle valve of each advancing piston to a specific value (e.g., 3.5MPa), the throttle valve can pass a larger flow rate while remaining under control, thus ensuring the six pistons receive continuously synchronous pressure.
3. Enabling Fast and Accurate Fault Diagnosis
Although fault diagnosis does not directly control precision, it ensures the system can operate at high precision for extended periods:
Inference from Fault Phenomena to Causes: The digital control system allows operators to retrieve or observe operating status and anomalies on the touch screen. For example, by checking whether the contact of the booster travel switch is disconnected during motor startup, it can be inferred whether the piston inside the booster has risen, thereby pinpointing the specific location of the fault.
Capturing Anomalies at Fixed Time/Fixed Pressure: For phenomena like "takes too long to reach overpressure," the touch screen can display that this phenomenon occurs at a fixed time and fixed pressure. Operators can use this information to capture the cause and location of the fault, preventing synthesis accuracy and results from being affected by equipment operational anomalies.
In conclusion, by introducing technologies such as PLC and pressure sensors, the digital control system elevated the control of complex process parameters (pressure, temperature, time, etc.) from the difficult-to-implement stage of relay logical control to a programmed control stage where parameters can be precisely set, monitored in real-time, and actively adjusted, thereby meeting the trend requirements for high-precision control in superhard material synthesis.